In 2010, the US Food and Drug Administration (FDA) issued a warning on the box of the anti-clotting drugClopidogrel that patients who do not metabolize the drug will not receive the full benefits of the drug. This, in essence, is a landmark that highlights the importance of personalized care in the emerging field of precision medicine. In retrospect, Clopidrogel’s failure among certain patients hardly seems surprising: patients are genetically diverse, and such variation affects patient’s response to particular therapies. Roughly 75% of the U.S. population does not metabolize medications normally and 2.2 million severe Adverse Drug Events (ADEs) occur in the U.S. every year. Genetics can account for 20-95% of the variability in an individual’s response to drugs. Medicare fined three-quarters of eligible hospitals for re-admissions in 2014. Current FDA guidance recommends that Drug-gene interactions should be considered similar in scope to drug-drug interactions. Precision medicine takes advantage of the genetic diversity that exists to tailor treatments to those patients who are most likely to respond.

Clopidogrel is a widely used anti-clotting drug and according to Dr. P. Manokar, MD, DM, Professor of Cardiology, Sri Ramachandra University “Clopidogrel is like a panacea of all cardiac and vascular diseases from Stroke prevention to Peripheral artery disease to coronary Interventions. It is the essence of pharmacotherapy for all Vascular Disease Scenarios.” When the outcomes of treatment are poor, it could prompt some patients from taking the treatment while the condition being treated could turn worse, wasting precious time, effort and money.

Dr. Abraham Ooman, a leading Cardiologist, has also shown interest in genetic testing, stating that here is a need for genetic testing to determine the response to Clopidogrel, especially during high risk cardiac interventions like left main stenting”, however, he adds a quick note of caution, “but clinical studies are unclear about how effective the current methods are.”When the approach to care is evidence based instead of resorting to a trial and error method of prescribing medications, it could help avoid side effects associated with drug use and could, possibly, lower health care costs. In recognition of the promise shown by precision medicine, Ex-President of the United States, Barack Obama, in 2015, announced a nationwide research called ‘the Precision Medicine Initiative’ for conditions associated with cardiovascular disease, neurodegenerative disease, cancer and autoimmune disorders. In Obama’s words, “most medical treatments have been designed for the ‘average patient’, treatments can be very successful for some patients but not for others.”

Though there have been considerable strides in the treatment of cardiovascular disease, cardiovascular disease related death is still one of the most common cause of death. This creates a need to utilize precision medicine to identify patients who would benefit from the treatment provided. As Dr. Manokar says “It is very difficult to predict who responds to clopidogrel unless you have an event as a consequence of clopidogrel resistance. You begin a search with your backs to the wall situation. Testing would allay the anxiety of the Doctor and the patient equally”

The importance of testing for responders, however, lies in the options that are available, as Dr. Manokar says, “The other treatment options are tricky. They come with a whole bag of indications and contraindications which make the options difficult to choose. Both Ticagelor and Prasugrel are niche molecules but need huge brainstorming before choosing as an alternative to Clopidogrel.” The enthusiasm shared by doctors and the regulators are shared by drug companies too with 28 percent of drugs that were approved by the FDA in 2015, considered to be precision medicine based therapies.

The concept of genetic testing is not new and is an essential medical tool that has been used by the medical community for decades to look deeper into the human body for myriad determinations. Chromosomes are investigated for carrier testing, newborn screening, prenatal diagnosis, diagnostic testing, paternity, genealogy and forensics testing. So, testing for responders is a natural progression and “Testing is always cost effective. It offers intangible benefits in terms of allaying anxiety, long term outcomes, more than the tangible benefits in terms of choice of drugs and duration of therapy,” said Dr. Manokar. Though, he further stated that the additional cost “is an important determinant of the number of patients that we would test routinely. It is important also with respect to Ticagelor switch since it is the most expensive drug in this group.”

Clinically, the use of pharmacogenetics could potentially include vast areas like new drug development, drug discovery research, the genetic testing of patients and clinical patient management. The ultimate aim of pharmacogenetics is to predict genetic response of patients to a specific drug to deliver the best possible medical treatment. By predicting the drug response of an individual, it will be possible to increase the success of therapies and reduce the incidence of adverse side effects. “Personalized medicine is the logical way forward, however, it should pass the necessary scientific scrutiny of clinical trials,” said Dr. Abraham stressing the need to accept this aspect of medical science as the way ahead.

A single method of treatment for everyone is unrealistic in the current understanding of medical science because of the complex interplay between genes, cell metabolism, proteins and environmental influences. As Dr. Manokar puts it, “future of pharmacology is going to be pharmacogenomics. Patient centric medicine and genome tailored pharmacotherapy will be the norm rather than the exception.”

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